This invention relates to recording apparatuses, and more particularly to a recording apparatus which is effectively used for a CAD (computer-aided automatic drafting device) which records data on a recording sheet of large size such as size A0.
Typical examples of an apparatus for recording data on a recording sheet of size A0 are a printing apparatus of photographic system and a recording apparatus of electrostatic recording system. They are extensively employed in a large number of fields. On the other hand, a CAD for facilitating the formation of design drawings has been put in practical use, and a variety of recording apparatuses for such a CAD have been also proposed in the art.
In recording data on a recording sheet of large size such as size A0, it is not preferable to use all the parts of the recording sheet simultaneously, because the recording apparatus which can record data in this manner is unavoidably intricate in construction. In order to overcome this difficulty, a recording means having a predetermined main scanning length is used to scan the recording sheet relatively in the auxiliary scanning direction.
In a recording apparatus of electrostatic recording system, for instance a charging member whose main scanning length is substantially equal to the width of a recording sheet is used to charge the recording sheet to form a latent image thereon, and the latter is developed by applying toner or ink droplets thereto, to form the image.
When the recording means scans the recording sheet in a relative mode, the following two methods are employed: In the first method, the recording means scans the recording sheet which is at rest. In the second method, the recording means is at rest, while the recording sheet is conveyed.
In this connection, in the case where it is required to accurately convey a large size recording sheet of large size such as that of size A0 with a plurality of coaxial rollers the cylindrical outer walls of those rollers must be polished with high precision.